AZURITY PHARMACEUTICALS, INC. v. ALKEM LABORATORIES LTD.
Before Murphy, Moore, and Chen. Appeal from the United States District Court for the District of Delaware.
Summary: Arguments and amendments made during prosecution of a parent application can provide “clear and unmistakable” evidence of a disclaimer of claim scope in a continuation application.
Azurity Pharmaceuticals sued Alkem Laboratories alleging Alkem’s Abbreviated New Drug Application (“ANDA”) infringed a patent directed to drinkable drugs for treating colon infections. Azurity’s patent was a continuation of another application (“’059 Application”) that had been rejected numerous times during prosecution over a prior-art reference (“Palepu”) which contained “a polar solvent including propylene glycol.” The district court determined that Azurity’s arguments and amendments during prosecution of the ’059 Application “clearly and unmistakably” disclaimed propylene glycol from the claimed invention. Because Alkem’s ANDA product contained propylene glycol and Azurity’s patent claims used the closed “consisting of” transition phrase, the district court found that Alkem’s ANDA did not infringe Azurity’s patent.
The district court also rejected Azurity’s argument that a discovery stipulation overcame the disclaimer of propylene glycol. Specifically, Azurity’s patent claims recited a “flavoring agent,” and the parties had stipulated that “[s]uitable flavoring agents for use in the Asserted Claims include flavoring agents with or without propylene glycol.” Azurity interpreted the stipulation to mean that products with flavoring agents that include propylene glycol could infringe regardless of the “consisting of” transition and disclaimer. However, the district court rejected that argument and found that the disclaimer of propylene glycol was dispositive.
The Federal Circuit affirmed. The Federal Circuit noted that, during prosecution of the ’059 Application, the examiner repeatedly cited Palepu as prior art and, at every opportunity, Azurity clearly and unmistakably distinguished its invention from Palepu by asserting the claimed formulations did not contain propylene glycol. Azurity argued that it did not disclaim propylene glycol because, during prosecution of another patent application (“’421 Application”), Azurity stated in an office action response that the ’059 Application did not disclaim propylene glycol. The Federal Circuit did not consider that statement relevant because the ’421 and ’059 Applications were prosecuted in parallel with each other and Azurity made that statement after the claims at issue were allowed. Finally, the Federal Circuit affirmed the district court’s conclusion that the parties’ stipulation did not preclude the disclaimer. Alkem contended in the stipulation that it did not infringe due to the presence of propylene glycol and the Federal Circuit found it implausible that Alkem would have conceded infringement just several lines later.
Editor: Sean Murray
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